Precision needed – Apprenticeship for Toolmaking Mechanic

In my blog series ‘What does…actually do?’, I (Arne Bauer) give readers an insight into the jobs that certain people at MANN+HUMMEL do. It is my job as a roving reporter to look over the shoulders of employees at the different locations in Germany. In Sonneberg, I spent some time shadowing toolmaking mechanic Daniel Hornig as he went about his work repairing massive tools that weigh several tons.

What does a toolmaking mechanic in Sonneberg actually do?

There are rows upon rows of workbenches in the toolmaking mechanics’ hall in Sonneberg. Here enormous machines are used to process steel and mould cubic tools. Whilst new tools are being produced at the front of the hall, Daniel Hornig can be found further back, repairing the tools that have already been put to use in the production halls. “I usually have to work quickly,” Hornig says. This is because the tools need to be ready and repaired by the time they are needed again.

The huge pieces of equipment, which often weighs several tons, are transported to the tool repairs zone by a forklift truck. Small tools may weigh less but this definitely does not make them easier to repair, as Hornig knows only too well: “Small tools are delicate and often extremely complex.” The setters who insert the tools into the machines provide us with a description of the problem on the repair order form. “I often have to go and get more information from the person who filled in the form,” explains Hornig. However, before doing that he first opens the tool, which is made up of two similar-sized parts. Sometimes he uses another piece of heavy equipment to do this. In normal operation, the two halves of the tool are pressed together by the machine, in order to mould the products in the centre.

In order to spot any deviations from the tool’s intended shape, which often measure only a few hundreths of a millimetre, Hornig also examines the end product and inserts it into the tool so he can identify where the damage is. Even the finest of cracks in the steel can cause undesirable burring of the plastic. To repair the tool, the toolmaking mechanic lifts it into position with an indoor crane and then dismantles it. This process has been known to last several hours.

“I often have to think hard before I come up with a solution.” Although it is easier for the tool manufacturers to produce the mould halves from one piece, when it comes to repairs it is actually better if they are made up of several segments. There are two reasons for this: the person carrying out the repairs can get to the part that needs to be repaired more quickly and, if in doubt, they can easily replace individual damaged parts.

Hornig has to be especially careful when he repairs tools with a built-in hot runner. His first step is to check if it is working. If it is faulty, Hornig removes the hot runner with the help of an electrician. He has to pay careful attention to the delicate cable in order to avoid damaging the hot runner system. The tools are always cleaned while they are being repaired. Once the tool is dismantled, Hornig is left holding a metal element the length of his thumb.

The element has a millimetre-deep cavity which is causing a plastic protrusion on the product. “Sometimes it would be nice for it to be a question of millimetres. Most of the time, we are dealing with tenths of a millimetre,” he says. Once his colleague has applied new material to the exact point on the laser welding device, Hornig machines the metal with an air grinder and his diamond files until he is satisfied with the end result. Once he has put the tool back together, it is taken back to the production area, where it is put back into operation until it next needs to be repaired again.

AuthorArne Bauer

Arne Bauer worked until March 2015 in Corporate Communications of MANN+HUMMEL as a trainee and work student . In his blog series, he introduced different MANN+HUMMEL job profiles as an inhouse reporter.